Optimization of synthesis of trimethylolpropane fatty acid esters under microwave irradiation by response surface methodology

Trimethylolpropane oleic acid ester was synthesized under microwave irradiation using trimethylolpropane(TMP) and oleic acid(OA) as materials.Effects of reaction time,reaction temperature,microwave power,the amount of catalyst and molar ratio of OA to TMP on the esterification rate of trimethylolpropane oleic acid ester were investigated.The optimum conditions were obtained by response surface methodology(RSM) as follows:reaction temperature 111.75℃,reaction time 16.08 min,molar ratio of OA to TMP was 3∶1,microwave power 637 W,the amount of catalyst 3.04%.Under the optimum conditions the esterification rate was 84.40%.Under the above optimum conditions,other trimethylolpropane fatty acid esters,such as trimethylolpropane lauric acid ester,trimethylolpropane myristic acid ester,trimethylolpropane capric acid ester and trimethylolpropane octanoic acid ester were synthesized,and their esterification rates were 80.97%,87.03%,80.73% and 81.24%,respectively.